I've been trying to get movies by their ID, but I receive an error message that my api key isn't valid (which seems unlikely to me). I am programming in C#.

The first thing I do is searching movies by title, for which I use the following: http://api.themoviedb.org/3/search/movie?query=[movie_title]&api_key=[my_api_key]

From the data which I receive here I want to get additional information, like movie genre, etc. For this I use the following: http://api.themoviedb.org/3/movie/[id]&api_key=[my_api_key]

When I do this, I get the following error message: {"status_code":7,"status_message":"Invalid API key: You must be granted a valid key."}

Which seems highly unlikely to me, as I used it just before to get the movie id, and then it worked. Is there something I am doing wrong, or with the format I use?

Any help would be appreciated! Thanks in advance